1. Field of the Invention
This invention relates, generally, to a repeater case construction that prevents overheating of the repeater case.
2. Description of the Prior Art
Repeater cases hold sensitive telecommunications equipment in hostile environments such as telephone poles exposed to the weather, manholes, and the like. A typical repeater case has twenty-four slots and is designed to hold twenty-four T1 telecommunication line modules.
Repeater cases designed to hold T1 line cards work well when performing that function. However, when High Density Subscriber Line (HDSL) modules are mounted in such repeater cases, overheating occurs because the cases are not designed to dissipate the heat generated by such modules. The HDSL modules are also larger in some cases than the T1 modules, and in some cases an HDSL module occupies only ever other slot in a repeater case.
The number of HDSL modules that may be fitted into a repeater case designed to hold T1 modules is limited not only by the larger size in some cases of the HDSL modules, but also by the fact that the HDSL modules generate more heat than T1 modules.
The known repeater cases also include acrylic plastic barriers that prevent accidental short circuits between printed circuit (PC) boards in the repeater case housing and individual conductors. The conductors pass through small openings formed in the acrylic plastic barriers and their respective free ends are hard-wired to the bottoms of such PC boards. The small openings formed in the acrylic plastic barriers make it somewhat difficult to connect the individual conductors to the PC boards, and the barriers themselves restrict air flow and thus contribute to heat build-up within the repeater case.
The repeater cases heretofore known also house a large PC board having opposing edges that are attached to opposite walls of the housing and which therefore inhibits air flow within the housing.
What is needed, then, is an improved repeater case construction. The needed repeater case would handle both T1 and HDSL modules in the absence of excessive heat buildup. It would also accommodate eighteen or more HDSL modules. It would provide enhanced clearance between the acrylic plastic barriers and the conductors. Moreover, it would provide better air flow around the PC board.
However, in view of the prior art taken as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this art how the needed repeater case could be provided.
The long-standing but heretofore unfulfilled need for an improved repeater case that overcomes the limitations of the prior art is now met by a new, useful, and nonobvious invention. The novel repeater case of this invention includes a base, a housing that surmounts the base, and a highly novel closure means that surmounts and closes the housing.
More particularly, the base has a bottom wall, upstanding side walls, and an open top. The housing has side walls, an open bottom and an open top; the base supports the housing and closes the open bottom of the housing.
The closure means that closes the open top of the housing is adapted to transfer heat within the base and housing to an environment external to the repeater case.
More specifically, the closure means is provided in the form of two thermal covers, each of which has a construction in common with the other.
The closure means further includes a plurality of heat-radiating fins formed in a top wall thereof.
A slot is formed in a top wall of the closure means and a heat transfer bar is disposed within the slot. A support bar is disposed adjacent an interior side of the top wall, and means are provided for interconnecting the heat transfer bar and the support bar.
Accordingly, heat within the housing rises to the top wall of the closure means, contacts the support bar and is transferred from the support bar to the heat transfer bar and to the heat-radiating fins.
A potting compound having a high coefficient of heat transfer is disposed between the support bar and the interior side of the top wall.
The closure means has a deep design to increase the volumetric capacity of the repeater case, thereby increasing the amount of heat that it can tolerate.
A plurality of sets of electrical connectors is positioned within the housing, each set of which is adapted to hold a telecommunications module. All of the telecommunications modules adapted to hold both HDSL and T1 modules.
A plurality of printed circuit boards are housed within the housing, there being one printed circuit board for each of the modules.
An opening is formed in the base for receiving a telecommunications cable. The telecommunications cable is divided into a plurality of sets of conductors, and each set of conductors is connected to a corresponding PC board.
A mounting means is provided for mounting a plurality of nonconductive barriers within the housing in vertically spaced apart relation to the PC boards, there being as many nonconductive barriers as there are PC boards. The nonconductive barriers, preferably formed of acrylic plastic, serve to prevent short circuits between the conductors and the PC boards.
The invention can also be defined as a method for cooling high density subscriber line modules in a repeater case, including the steps of providing a closure means for the repeater case and pressurizing an internal volume of the repeater case with a cooling atmosphere in the form of a gaseous fluid. Further steps include the steps of forming heat-radiating fins on an external surface of the closure means, positioning materials having a high coefficient of heat transfer in contact with an interior surface of the closure means and placing the materials in heat conducting relation to the heat radiating fins through an opening formed in the closure means.
The steps of the novel method further include the step of providing multiple printed circuit boards within the repeater case in spaced apart relation to one another, each of the printed circuit boards being dedicated to an associated module so that the spacing between the printed circuit boards enhances the cooling effect of the cooling atmosphere.
Additional method steps include positioning an electrically insulating barrier means in spaced apart relation to each of the printed circuit boards to facilitate connection of conductors to the printed circuit boards and to enhance the cooling effect of the cooling atmosphere, and forming the closure means so that it has a deep construction to increase its volumetric capacity for dissipating heat.
It is therefore understood that it is an important object of this invention to provide a repeater case capable of housing HDSL modules and dissipating the heat generated thereby.
A more specific object is to provide a repeater case having thermal covers that dissipate heat.
Another more specific object is to provide a repeater case having improved air flow therewithin.
Still another object is to provide a repeater case having acrylic plastic barriers that provide enhanced clearance for conductors as well as enhanced air flow.
Another object is to improve air flow within a repeater case by providing a design where the PC board of the prior art is divided into a number of smaller PC boards to further enhance the air flow within the repeater case.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be set forth in the claims.